II 



BUTTER 



'39 



3. Indirect Determination of Fat. 



By determining the percentage of water and of non-fat in 

 butter, and then subtracting these numbers from 100, the 

 percentage of fat can be obtained. The same degree of 

 accuracy as with the direct estimation is not, however, to be 

 reached, for it can easily happen that the analytical errors in 

 the water and non-fat determinations are added together, and 

 so a serious difference results. 



(b) Practical Methods. 

 Bernstein s Method. 



Of the numerous practical methods for determining the 

 amount of fat in butter, mention will only be made of that due 

 to Alex. Bernstein, 1 for it is the only one that 

 gives applicable results. 



The necessary apparatus 2 is shown in Fig. 

 57, and consists of a glass cylinder, a, and a 

 tube, 5, in which the estimation is made. The 

 glass cylinder, a, is closed by a wooden stop- 

 per, c, into which the tube, fr, also fits. Rubber 

 stoppers close each end of tube, b. A small 

 syringe for measuring out glycerine also 

 belongs to the apparatus. 



To carry out the test, the tube, b, which 

 must be quite clean and dry, is closed by 

 the two rubber stoppers ; the smaller of these 

 must be so adjusted as to reach to the black 

 mark on the tube. The apparatus then has 

 the appearance shown in the sketch. 



After the larger stopper has been removed, 

 10 g. of butter are weighed out upon a strip 

 of parchment paper (7x4 cm.), an accurate 

 balance being used. Two c.c. of glycerine 

 (28 Beaume) are measured into the tube, and 

 afterwards the paper containing the butter is 

 slipped in. Enough pure benzine (petroleum ether) is added 



1 Milch- Zeituiut, 1905, No. 18. 



2 To be had from Alex. Bernstein, 9 Magdeburgerstrasse, Berlin. 



FIG. 57. Appara- 

 tus for Bernstein's 

 Method. 



